Electrical attachment-plug



un b14050 A. E. HELLEHSTEDT.

ELECTRICAL ATTACHMENT PLUG.

APPLICATION FILED 8.1.1918.

Patnted Mar. 22, 1921.

UNITED STATES PATENT OFFICE.

AXEL EDWALD HELLERS-TEDT, or GREAT FALLS, MONTANA,

ELECTRICAL ATTACHMENT-PLUG.

Specification of Letters Patent. P t t d u 22, 1921 Application filedApril 1, 1918. Serial No. 226,002.

ordinary electric socket, such as is used in' connection with theelectric bulb.

An important object of the invention is to provide a device of the abovementioned character, which is of simplified construction, cheap tomanufacture, and convenient in use.

A further ob'ectof the invention is to provide means or clamping orbinding the electric cord with the plug at a separate point'from theattachment of the wires of the cord with the contact elements of theplug, thereby taking up strain from the wires at their points ofattachment.

Other objects and advantages of the invention will be apparent duringthe course of the following description.

In the accompanying drawings forming a part of this specification and inwhich like numerals are employed to designate like parts throughout thesame,

Figurel is a side elevation of an attach ment plug embodying myinvention,

Fig. 2 is a central vertical longitudinal sectional view through thesame,

F ig. 3 is a similar view taken at a ri ht angle to the showing in Fig.2, parts being omitted,

Fig. 4 is a plan view of the same, I 1

Fig. 5 is a plan view of the clamping elements or bushing, and,

Fig. 6 is a side elevation of the same.

In the drawings, wherein for the purpose nates the body portion of theattachment plug,-which is preferably formed of insulating material,suchas porcelain, glass or the like. This body portion is provided withan annular flange 11, to one side of which is a tapered portion 12,leading to a reduced portion 13. This reduced portion has a taperedportion 14, atthe end thereof, as

' shown. Arranged upon the large end of the body portion 10 is a cap orend member 15, having openings for the reception of screws or bolts 16,the heads of which are disposed in recesses 17, as shown. These screwsor bolts 16 engage with tapered nuts 18, arranged within recesses 19,and anchored therem by means of cement 20 or the like. Of course anyother suitable means may be employed to hold the cap 15 upon the bodyportion 10.

The body portion 10 is thereof with a longitudinal opening includmg aninner portion 21, which is cylindrical, and an outer portion 22 which istapered, and decreases in diameter inwardly. As more clearly shown inFig. 2, a longitudinal passage 23 is formed through the body providedcentrally portion 10 and leads into the inner end of I the openingportion 21. The opening 23 extends through the tapered portion 14, asshown. The body portion 10 is further provided with a laterallyextending opening or passage 24, extending through the tapered port on12 and leadin portlon 21, as shown. he cap 15 has a lon- .gitudlnallyextending c 26 having its inner en shown at 27, forming a clearly shownin Fig. 3.

The numeral 29 designates an electrical cord, suitably wrapped withinsulating materlal, as is customary, and embodying insulated w res 30and 31, which pass through the openings 24 and 23 respectively, asshown. The wire 30 has electrical engagement with a head 32', formedupon a spiral contact element 33. The head 32 is apertured for thepassage of a screw 34, engagmg a tapered nut 35,, anchored in the recess36, bymeans of cement 37 or the like. The head of the screw 34 iscountersunk, to be counterbored, as shoulder 28,, as

substantially flush with the periphery of the portion 14, the head 32fitting in a recess 32'. The wire 31 is clamped to a metallic plate. 38by means of a screw 39, havin I a large flat ead 40, serving as atermi-The'screw 39 has screw-threaded enshown at 45 and extends into a radialrelindrical opening I into the opening eess 45, thereby attaching suchfree end to the portion '13.

In order that all strain may be taken off of the wires 30 and 31 attheir points of attachment with the contact elements I provide aclamping device or bushing 46, including a cylindrical body portion *7,to engage within the counterbore 27 and a tapered expansible portion 48to engage within'the tapered opening portion 22. The tapered portion 48has longitudinal slots 49 and is further provided upon its interior withteeth 50. It is obvious that by moving the bushing 46 inwardly thetapered portion 48 is contracted and the teeth 50 thereof contact withthe cord 29, in a manner to prevent the cord being moved outwardly withrelation thereto.

It is to be understood that the form of my invention herewith shown anddescribed is to be taken as a preferred example of the same and thatvarious changes in the shape, size, and arrangement of parts may beresorted to without departing from the spirit of my invention or thescope of the subjoined claim. c

Having thus described my invention, I claiini In an electrical plugattachments the combination with a plug embodying a body portion havingan inwardly tapered longitudinal bore near its outer end; of a capmounted at the outer end of the body portion and having a centrallongitudinal bore in alinement with the bore in said body portionadapted to receive a conduit, the bore being reduced near the outer endof said cap to provide an annular shoulder, means for attaching said capto the body portion oi the plug, and a unitary bushing comprising acylindrical portion received in the inner bore of said cap and held inposition by said shoulder. and having a conical portion received in thetapered bore of said body portion. said bushing being provided with acentral longitudinal opening for the passage of said conduit. theconical section of said bushing being provided with a plurality ofradial slots extending to and termitiating at the lower extremity of thecylindrical portion of the bushing, the lower portion of the bore ofsaid bushing being prov1ded with teeth projecting inwardly beyond thebore of the upper portionof the bushing and adapted to grip said conduitto prevent longitudinal movement thereof with respect to the bodyportion. In testimony whereof I aiiix my signature ;n presence or twowitnesses.

ALEX EDWALD HELLERSTEDT.

